User Manual
Appendix D
GFK-1742F
Jan 2020
Tuning Digital and Analog Servo Systems
435
7.
With the Drive Enabled %Q bit ON and no servo motion commanded, adjust the
servo drive so no motion is generated. The velocity loop integral term MUST be set
to 0 to properly complete this step.
8.
Once correct basic operation has been achieved, the velocity loop requires tuning.
The section "Tuning the Torque Mode Velocity Loop" contains a basic procedure for
tuning the loop. NOTE: The tuning procedure for Torque Mode velocity regulators is
DIFFERENT from Digital Mode Velocity regulators. The user should NOT proceed to
tuning the Position Loop until the velocity loop tuning is complete.
9.
Once the velocity regulators have been tuned, the position loop tuning and setup
can be completed. Initially set the Pos Loop Time Constant (0.1 ms) configuration
parameter to a high value (typically 100 ms or a value of 1000 in the configuration).
10.
Turn on the %Q Jog Plus bit. Confirm that the servo moves in the proper direction
and that the Actual Velocity reported by the Motion Mate DSM314 in the %AI table
matches the configured Jog Velocity. If Motion Programs will use acceleration
higher than the Jog Acceleration, it may be necessary to increase Jog Acceleration so
that Abort All Moves and Normal Stop actions will operate as expected.
11.
Check for proper operation of the Find Home cycle by momentarily turning on the
%Q Find Home bit (the Drive Enabled %Q bit must also be maintained ON). The axis
should move towards the Home Switch at the configured Find Home Velocity, then
seek the Encoder Marker at the configured Final Home Velocity. If necessary, adjust
the configured velocities and the location of the Home Switch for consistent
operation. The final Home Switch transition MUST occur at least 10 ms before the
Encoder Marker Pulse is encountered. The physical location of Home Position can
then be adjusted by changing the Home Offset value in the Configuration Software.
12.
Monitor servo performance and use the %Q Jog Plus and Jog Minus bits to move the
analog servo motor in each direction. The Position Loop Time Constant can be
temporarily modified by placing the correct command code in the %AQ table. For
most systems the Position Loop Time Constant can be reduced until some servo
instability is noted, then increased to a value approximately 50% higher. Once the
correct time constant is determined, the DSM314 configuration should be updated
using the Configuration Software. Velocity Feedforward can also be set to a non-
zero value (typically 90-100 %) for optimum servo response.
Note:
For proper servo operation, the Configuration entry for Velocity at Max Cmd MUST be set
to maximum servo velocity (in User Units/sec) that the system or process allows.